1. Field of the Invention
The present invention relates to a golf club head by which an improvement of carry can be expected.
2. Description of the Related Art
In recent years, there has been proposed a golf club head in which an inner portion is formed hollow. The head mentioned above has a metal face portion for hitting a ball. Further, the face portion includes a center portion having a large thickness and the peripheral portion surrounding the center portion and having a smaller thickness than that of the center portion.
In the head mentioned above, a specific frequency of the head gets close to a specific frequency of the ball. Accordingly, an energy loss generated at a time of collision between the head and the ball is reduced, and a kinetic energy of the head is efficiently transferred to the ball. As a result, an initial velocity at a time of hitting the ball is increased, and an improvement of carry can be expected. In other words, the head mentioned above has a large restitution coefficient.
However, USGA and R&A reform the golf rules and limit the maximum value of the restitution coefficient of the head. The head described above goes beyond the maximum value of the restitution coefficient at a high possibility, and there is a possibility that the head described above can not be used in an official tournament hereafter. Accordingly, in order to provide a head which can be used in the official tournament while obtaining a long carry, it is necessary to improve the other matters than the restitution coefficient.